DESCRIPTION (from applicant's abstract): The implementation of newborn hearing screening practices is leading to more children with hearing loss being identified in infancy. Parents and hearing professionals are being faced with making decisions about intervention strategies for these young children. This study addresses an issue of critical importance to those who must decide whether and when to provide a young deaf child with a cochlear implant. Research in child language acquisition suggests that improved auditory stimulation should be introduced as early as possible to take advantage of the infant's propensity to learn language. On the other hand, the trauma to a family upon learning that their child is deaf and the difficulties professionals encounter in obtaining reliable behavioral thresholds at very young ages are among reasons cited for waiting until the child is older to perform implant surgery. The consequences of delaying the decision to provide an implant could be substantial. Previous work by the principal investigator on the acquisition of early communicative behaviors by normal hearing and deaf children under 54 months of age documents the dramatic delay exhibited by oral deaf children in many important precursors of normal language. Development of these behaviors is predictive of their spoken language competence several years later. If the documented speech perception benefits available from a cochlear implant can ameliorate these deficits, then early implantation is critical for families who value development of spoken language in their deaf child. The aim of this study is to examine the effects of implantation during the crucial language-learning period before 3 years of age on communication and language skills exhibited at 3 and 4 years of age. Over 5 years, 50 children receiving an implant before 3 years of age who are enrolled in oral education programs across the country will be videotaped in conversational interaction when they are 3 1/2 years and again at 4 1/2 years of age. The communicative functions, lexical, and syntactic characteristics of their language will be quantified and analyzed in relation to the age at which they received an implant: 18-23 months or 30-35 months. Results will be compared with our existing data on normally hearing 3 1/2 and 4 1/2 year olds. The design will allow for age of implantation effects to be measured while holding duration of implant use constant. It is hypothesized that the importance of early auditory experience will be reflected in communicative function and language use that is closer to that of normally hearing age mates the earlier the child received the implant.